JP2011088413A - Liquid ejecting device and liquid ejecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the deviation of a liquid impact position in a liquid ejecting device and a liquid ejecting method. <P>SOLUTION: The liquid ejecting device is equipped with: a head that ejects liquid to a medium; a head moving part that moves the head in a moving direction; a temperature acquiring part that acquires temperature of the head; and a controller that controls the head moving part and the head, the controller that allows the head to eject the liquid while moving the head at first speed when the temperature acquired by the temperature acquiring part is over first predetermined temperature, and allows the head to eject the liquid while moving the head at second speed lower than the first speed when the temperature acquired by the temperature acquiring part is equal to or under the first predetermined temperature. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid ejection apparatus and a liquid ejection method.

  2. Description of the Related Art An ink jet printer that ejects ink while moving a head to form an image is used. Some printers form images by ejecting ink in both the forward and backward directions of the head.

  In a printer that ejects ink in both directions, in order to improve the image quality of the image formed on the medium, the target landing position of the ink when the head is moving in the forward direction and in the backward direction If they are at the same position, the landing positions of the inks should be the same. For this purpose, a pattern for inspecting the ink landing position in the forward path and the ink landing position in the backward path is printed, and the ink ejection timing is corrected based on this pattern. Then, the landing position of the head in the forward direction and the landing position in the return direction are adjusted to coincide.

JP 2002-205385 A JP 2003-374743 A

By the way, as a characteristic of the liquid to be used, there is one having a sharper viscosity change on the low temperature side than on the high temperature side. When such a liquid is ejected from the head, the ejection speed rapidly decreases on the low temperature side, and therefore, the correction of the landing position may not be appropriately performed in the above-described ejection timing correction. Therefore, even in such a case, it is desirable to reduce the deviation of the liquid landing position.
The present invention has been made in view of such circumstances, and an object thereof is to reduce the deviation of the landing position of the liquid.

The main invention for achieving the above object is:
A head for discharging liquid onto the medium;
A head moving unit for moving the head in the moving direction;
A temperature acquisition unit for acquiring a temperature related to the head;
A control unit for controlling the head moving unit and the head, wherein when the temperature acquired by the temperature acquisition unit exceeds a first predetermined temperature, the head is moved at a first speed to discharge the liquid; A controller that moves the head at a second speed slower than the first speed to discharge the liquid when the temperature acquired by the temperature acquisition unit is equal to or lower than the first predetermined temperature;
It is a liquid discharge apparatus provided with.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

It is explanatory drawing which showed the external appearance structure of the printing system. 1 is a block diagram of an overall configuration of a printer according to an embodiment. FIG. 3A is a schematic diagram of the overall configuration of the printer of the present embodiment, and FIG. 3B is a cross-sectional view of the overall configuration of the printer of the present embodiment. FIG. 4A schematically shows the configuration of the linear encoder 51, and FIG. 4B schematically shows the configuration of the detection unit 466. 5A and 5B are timing charts showing waveforms of two output signals of the detection unit 466 when the carriage motor 42 is rotating forward and when the carriage motor 42 is rotating forward. FIG. 6A is a diagram illustrating the structure of the head 41, and FIG. 6B is an explanatory diagram illustrating the arrangement of nozzles on the lower surface of the head 41. FIG. 7A is an explanatory diagram of a drive circuit of the head unit 40, and FIG. 7B is an explanatory diagram of the drive circuit. It is a timing chart for explanation of each signal. It is a figure explaining the landing position of the ink in bidirectional printing. FIG. 10A is an explanatory diagram of a pattern for inspecting the deviation of the ink landing position, and FIG. 10B is an explanatory diagram of the pattern after the ink ejection timing is adjusted. FIG. 11A is a diagram for explaining the relationship between the original signal before adjusting the ink ejection timing and the control signal, and FIG. 11B is a diagram for explaining the relationship between the original signal after adjusting the ink ejection timing and the control signal. is there. It is a figure which shows the relationship of the viscosity of the ink with respect to temperature and temperature. 5 is a flowchart of print processing in the first embodiment. FIG. 6 is a diagram illustrating ink landing positions when the moving speed of a head 41 is slowed. It is a flowchart of the printing process in 2nd Embodiment.

  At least the following matters will become clear from the description of the present specification and the accompanying drawings.

A head for discharging liquid onto the medium;
A head moving unit for moving the head in the moving direction;
A temperature acquisition unit for acquiring a temperature related to the head;
A control unit for controlling the head moving unit and the head, wherein when the temperature acquired by the temperature acquisition unit exceeds a first predetermined temperature, the head is moved at a first speed to discharge the liquid; A controller that moves the head at a second speed slower than the first speed to discharge the liquid when the temperature acquired by the temperature acquisition unit is equal to or lower than the first predetermined temperature;
A liquid ejection apparatus comprising:
By doing in this way, the shift | offset | difference of the landing position of a liquid can be reduced.

  In this liquid ejection apparatus, it is preferable that the determination as to whether or not the temperature acquired by the temperature acquisition unit is equal to or lower than the first predetermined temperature is performed for each page of the medium. By doing so, it is possible to discharge the liquid according to the temperature related to the head for each page, and to reduce the deviation of the landing position of the liquid.

  The determination as to whether or not the temperature acquired by the temperature acquisition unit is equal to or lower than the first predetermined temperature may be performed every predetermined time. By doing in this way, the liquid according to the temperature regarding a head is discharged for every predetermined time, and the shift | offset | difference of the landing position of a liquid can be reduced.

In addition, when the temperature acquired by the temperature acquisition unit exceeds the first predetermined temperature, the control unit moves the head at the first speed, and discharges the liquid in the forward path and the return path in the movement direction. When the temperature acquired by the temperature acquisition unit controlled in the first mode is less than the first predetermined temperature and exceeds a second predetermined temperature lower than the first predetermined temperature, the head is moved at the second speed. When the temperature acquired by the temperature acquisition unit is equal to or lower than the second predetermined temperature, either the forward path or the return path in the movement direction is controlled. On the other hand, it is desirable to control in the third mode in which the liquid is ejected when the head is moving.
By doing so, it is possible to reduce the deviation of the landing position of the liquid by performing either so-called bidirectional printing or unidirectional printing according to the temperature related to the head.

In addition, when the temperature acquired by the temperature acquisition unit is equal to or lower than the second predetermined temperature and exceeds a third predetermined temperature lower than the second predetermined temperature, the control unit determines which of the forward path and the return path in the moving direction. On the other hand, control is performed in a third mode in which the liquid is ejected when the head is moving, and when the temperature acquired by the temperature acquisition unit is equal to or lower than the third predetermined temperature, the forward path and the return path in the moving direction are controlled. In any one of the cases, it is desirable to perform control in the fourth mode in which the liquid is ejected when the head is moving at a slower speed than in the third mode.
By doing so, it is possible to reduce the displacement of the landing position of the liquid by changing the moving speed of the head according to the temperature related to the head.

  In addition, it is preferable that the moving speed of the head is set so that the area of an image formed per unit time on the medium is larger in the second mode than in the third mode. . By doing so, it is possible to reduce the deviation of the landing position of the liquid while increasing the printing speed as much as possible.

  Further, it is desirable that the viscosity change with respect to the temperature of the liquid is steeper as the temperature of the liquid is lower. By doing so, even when a liquid whose viscosity changes more rapidly as the temperature is lower is used, the deviation of the landing position of the liquid can be reduced.

Obtaining a temperature associated with a head that ejects liquid onto the medium;
When the temperature exceeds a predetermined temperature, the head is moved at a first speed to discharge the liquid. When the temperature is equal to or lower than the predetermined temperature, the head is moved at a second speed that is slower than the first speed. Moving and ejecting the liquid;
A liquid ejection method comprising:
By doing in this way, the shift | offset | difference of the landing position of a liquid can be reduced.

=== First Embodiment ===
<Configuration of printing system>
An embodiment of a printing system (computer system) will be described with reference to the drawings. However, the description of the following embodiments includes embodiments relating to a computer program and a recording medium on which the computer program is recorded.

  FIG. 1 is an explanatory diagram showing an external configuration of a printing system. The printing system 100 includes a printer 1, a computer 110, a display device 120, an input device 130, and a recording / reproducing device 140. The printer 1 is a printing apparatus that prints an image on a medium such as paper, cloth, or film. The computer 110 is electrically connected to the printer 1 and outputs print data corresponding to the image to be printed to the printer 1 in order to cause the printer 1 to print an image. The display device 120 has a display and displays a user interface such as an application program or a printer driver. The input device 130 is, for example, a keyboard 130A or a mouse 130B, and is used for operating an application program, setting a printer driver, or the like along a user interface displayed on the display device 120. As the recording / reproducing device 140, for example, a flexible disk drive device 140A or a CD-ROM drive device 140B is used.

  A printer driver is installed in the computer 110. The printer driver is a program for realizing the function of displaying the user interface on the display device 120 and the function of converting the image data output from the application program into print data. This printer driver is recorded on a recording medium (computer-readable recording medium) such as a flexible disk FD or a CD-ROM. Alternatively, the printer driver can be downloaded to the computer 110 via the Internet. In addition, this program is comprised from the code | cord | chord for implement | achieving various functions.

<Inkjet printer configuration>
FIG. 2 is a block diagram of the overall configuration of the printer of this embodiment. FIG. 3A is a schematic diagram of the overall configuration of the printer of this embodiment. FIG. 3B is a cross-sectional view of the overall configuration of the printer of this embodiment. Hereinafter, the basic configuration of the printer of this embodiment will be described.

  The printer of this embodiment includes a transport unit 20, a carriage unit 30, a head unit 40, a detector group 50, and a controller 60. The printer 1 that has received print data from the computer 110, which is an external device, controls each unit (the conveyance unit 20, the carriage unit 30, and the head unit 40) by the controller 60. The controller 60 controls each unit based on the print data received from the computer 110 and forms an image on paper. The situation in the printer 1 is monitored by a detector group 50, and the detector group 50 outputs a detection result to the controller 60. The controller 60 that receives the detection result from the detector group 50 controls each unit based on the detection result.

  The transport unit 20 is for feeding a medium (for example, the paper S) to a printable position and transporting the paper by a predetermined transport amount in a predetermined direction (hereinafter referred to as a transport direction) during printing. That is, the transport unit 20 functions as a transport mechanism that transports paper. The transport unit 20 includes a paper feed roller 21, a transport motor 22 (also referred to as a PF motor), a transport roller 23, a platen 24, and a paper discharge roller 25. However, in order for the transport unit 20 to function as a transport mechanism, all of these components are not necessarily required. The paper feed roller 21 is a roller for automatically feeding the paper inserted into the paper insertion slot into the printer. The paper feed roller 21 has a D-shaped cross section, and the length of the circumferential portion is set to be longer than the transport distance to the transport roller 23. 23 can be conveyed. The transport motor 22 is a motor for transporting paper in the transport direction, and is constituted by a DC motor. The transport roller 23 is a roller that transports the paper S fed by the paper feed roller 21 to a printable area, and is driven by the transport motor 22. The platen 24 supports the paper S being printed. The paper discharge roller 25 is a roller for discharging the printed paper S to the outside of the printer. The paper discharge roller 25 rotates in synchronization with the transport roller 23.

  The carriage unit 30 is for moving (also referred to as “scanning”) the head in a predetermined direction (hereinafter referred to as a moving direction). The carriage unit 30 includes a carriage 31 and a carriage motor 32 (also referred to as a CR motor). The carriage 31 can reciprocate in the moving direction. (Thus, the head moves along the moving direction.) The carriage 31 detachably holds an ink cartridge that stores ink. The carriage motor 32 is a motor for moving the carriage 31 in the movement direction, and is constituted by a DC motor.

  The head unit 40 is for ejecting ink onto paper. The head unit 40 has a head 41. The head 41 has a plurality of nozzles that are ink discharge portions, and discharges ink intermittently from each nozzle. The head 41 is provided on the carriage 31. Therefore, when the carriage 31 moves in the movement direction, the head 41 also moves in the movement direction. Then, by intermittently ejecting ink while the head 41 is moving in the moving direction, dot lines (raster lines) along the moving direction are formed on the paper. The head unit 40 acquires data for driving the head via the cable 45 from the control unit on the printer main body side. The cable 45 is a flexible belt-like cable, and electrically connects the printer main body and the carriage 31.

  The detector group 50 includes a linear encoder 51, a rotary encoder 52, a paper detection sensor 53, an optical sensor 54, and the like. The linear encoder 51 is for detecting the position of the carriage 31 in the moving direction. The rotary encoder 52 is for detecting the rotation amount of the transport roller 23. The paper detection sensor 53 is for detecting the position of the leading edge of the paper to be printed. The paper detection sensor 53 is provided at a position where the position of the leading edge of the paper can be detected while the paper feed roller 21 feeds the paper toward the transport roller 23. The paper detection sensor 53 is a mechanical sensor that detects the leading edge of the paper by a mechanical mechanism. More specifically, the paper detection sensor 53 has a lever that can rotate in the transport direction, and this lever is disposed so as to protrude into the paper transport path. For this reason, since the leading edge of the paper comes into contact with the lever and the lever is rotated, the paper detection sensor 53 detects the position of the leading edge of the paper by detecting the movement of the lever. The optical sensor 54 is attached to the carriage 31. The optical sensor 54 detects the presence or absence of paper by the light receiving unit detecting reflected light of light irradiated on the paper from the light emitting unit. The optical sensor 54 detects the position of the edge of the paper while being moved by the carriage 41. Since the optical sensor 54 optically detects the edge of the paper, the detection accuracy is higher than that of the mechanical paper detection sensor 53.

  The controller 60 is a control unit for controlling the printer. The controller 60 includes an interface unit 61, a CPU 62, a memory 63, and a unit control circuit 64. The interface unit 61 is for transmitting and receiving data between the computer 110 which is an external device and the printer 1. The CPU 62 is an arithmetic processing unit for controlling the entire printer. The memory 63 is for securing an area for storing the program of the CPU 62, a work area, and the like, and has storage means such as a RAM and an EEPROM. The CPU 62 controls each unit via the unit control circuit 64 in accordance with a program stored in the memory 63.

  FIG. 4A schematically shows the configuration of the linear encoder 51. The linear encoder 51 includes a linear encoder code plate 564 and a detection unit 566. The linear encoder code plate 564 is attached to the frame side inside the inkjet printer 1 as shown in FIG. 3A. On the other hand, the detection unit 566 is attached to the carriage 31 side. When the carriage 31 moves along the guide rail 36, the detection unit 566 relatively moves along the linear encoder code plate 564. Accordingly, the detection unit 566 detects the movement amount of the carriage 31.

<Configuration of detection unit>
FIG. 4B schematically shows the configuration of the detection unit 566. The detection unit 566 includes a light emitting diode 552, a collimator lens 554, and a detection processing unit 556. The detection processing unit 556 includes a plurality of (for example, four) photodiodes 558, a signal processing circuit 560, and, for example, two comparators 562A and 562B.

  When the voltage Vcc is applied to both ends of the light emitting diode 552 via a resistor, light is emitted from the light emitting diode 452. This light is condensed into parallel light by the collimator lens 554 and passes through the linear encoder code plate 564. The linear encoder code plate 564 is provided with slits at predetermined intervals (for example, 1/180 inch (1 inch = 2.54 cm)).

  The parallel light that has passed through the linear encoder code plate 564 enters each photodiode 558 through a fixed slit (not shown) and is converted into an electrical signal. The electric signals output from the four photodiodes 558 are subjected to signal processing in the signal processing circuit 560, the signals output from the signal processing circuit 560 are compared in the comparators 562A and 562B, and the comparison result is output as a pulse. The pulses ENC-A and ENC-B output from the comparators 562A and 562B become the output of the linear encoder 51.

<Output signal>
5A and 5B are timing charts showing waveforms of two output signals of the detection unit 566 when the carriage motor 32 is rotating forward and when the carriage motor 32 is rotating forward. As shown in FIGS. 5A and 5B, the phase of the pulse ENC-A and the pulse ENC-B are different from each other by 90 degrees both when the carriage motor 32 is rotating forward and when it is rotating backward. When the carriage motor 32 is rotating forward, that is, when the carriage 31 is moving along the guide rail 36, the pulse ENC-A is 90 degrees more than the pulse ENC-B, as shown in FIG. 5A. When the phase advances and the carriage motor 32 reverses, the phase of the pulse ENC-A is delayed by 90 degrees from the pulse ENC-B as shown in FIG. 5B. One cycle T of the pulse ENC-A and the pulse ENC-B is equal to the time during which the carriage 41 moves through the slit interval of the linear encoder code plate 564.

  Then, rising edges of the output pulses ENC-A and ENC-B of the linear encoder 51 are detected, the number of detected edges is counted, and the rotational position of the carriage motor 32 is calculated based on the counted value. The This count is incremented by “+1” when one edge is detected when the carriage motor 32 is rotating forward, and is “−1” when one edge is detected when rotating reversely. Is added. The period of each of the pulses ENC-A and ENC-B is equal to the time from the passage of a slit through the detection unit 566 to the passage of the next slit through the detection unit 566 of the linear encoder code plate 564. In addition, the pulse ENC-A and the pulse ENC-B are different in phase by 90 degrees. For this reason, the count value “1” of the count corresponds to ¼ of the slit interval of the linear encoder code plate 564. Thus, if the count value is multiplied by ¼ of the slit interval, the amount of movement of the carriage motor 32 from the rotational position corresponding to the count value “0” can be obtained based on the multiplication value. At this time, the resolution of the linear encoder 51 is ¼ of the slit interval of the linear encoder code plate 564.

  FIG. 6A is a diagram for explaining the structure of the head 41. In the figure, a nozzle Nz, a piezo element PZT, an ink supply path 402, a nozzle communication path 404, and an elastic plate 406 are shown.

  Ink is supplied to the ink supply path 402 from an ink tank (not shown). These inks and the like are supplied to the nozzle communication path 404. A drive signal pulse to be described later is applied to the piezo element PZT. When a pulse is applied, the piezo element PZT expands and contracts in accordance with the pulse signal, causing the elastic plate 406 to vibrate. An amount of ink droplets corresponding to the amplitude of the pulse is ejected from the nozzle Nz.

  Further, the thermistor 502 (corresponding to a temperature acquisition unit) is attached to the head 41. The temperature is output to the controller 60. Thus, by attaching the thermistor 502 to the head 41, the temperature of the head 41 can be acquired.

<About nozzle>
FIG. 6B is an explanatory diagram showing the arrangement of nozzles on the lower surface of the head 41. On the lower surface of the head 41, a black ink nozzle row K, a cyan ink nozzle row C, a magenta ink nozzle row M, and a yellow ink nozzle row Y are formed. Each nozzle row includes a plurality of nozzles (180 in this embodiment) that are ejection openings for ejecting ink of each color.

  The plurality of nozzles in each nozzle row are aligned at a constant interval (nozzle pitch: k · D) along the transport direction. Here, D is the minimum dot pitch in the carrying direction (that is, the interval at the highest resolution of dots formed on the paper S). K is an integer of 1 or more. For example, when the nozzle pitch is 180 dpi (1/180 inch) and the dot pitch in the transport direction is 720 dpi (1/720), k = 4.

  The nozzles in each nozzle row are assigned a lower number in the downstream nozzle (# 1 to # 180). That is, the nozzle # 1 is located downstream of the nozzle # 180 in the transport direction. Each nozzle is provided with a piezo element (not shown) as a drive element for driving each nozzle to eject ink droplets.

<About driving the head>
FIG. 7A is an explanatory diagram of a drive circuit of the head unit 40. This drive circuit is provided in the unit control circuit 64 described above, and includes an original drive signal generation unit 644A and a drive signal shaping unit 644B, as shown in FIG. Such drive circuits for the nozzles # 1 to # 180 are provided for each nozzle group, that is, for each nozzle row of each color of black (K), cyan (C), magenta (M), and yellow (Y). Yes. In addition, the piezo elements are individually driven for each nozzle. In the figure, the numbers in parentheses at the end of each signal name indicate the number of the nozzle to which the signal is supplied.

  When a voltage having a predetermined time width is applied between the electrodes provided at both ends of the piezoelectric element, the piezoelectric element expands according to the voltage application time and deforms the side wall of the ink flow path. As a result, the volume of the ink flow path contracts in accordance with the expansion and contraction of the piezo element, and the ink amount corresponding to the contraction is ejected from the nozzles # 1 to # 180 of the respective colors as ink droplets.

The original drive signal generator 644A generates an original signal ODRV that is used in common by the nozzles # 1 to # 180. The original signal ODRV is a signal including a plurality of pulses within the main scanning period for one pixel (within the time during which the carriage 41 crosses the interval of one pixel).
The drive signal shaping unit 644B receives the original signal ODRV from the original drive signal generation unit 644A and the print signal PRT as serial data.

  FIG. 7B is an explanatory diagram of a drive circuit. The print signal PRT is serial-parallel converted by a circuit as shown in FIG. 7B using 360 shift registers, and converted to PRT (i) indicating ON / OFF of each nozzle. The drive signal shaping unit 644B shapes the original signal ODRV according to the level of the print signal PRT (i), and outputs it as the drive signal DRV (i) toward the piezoelectric elements of the nozzles # 1 to # 180. The piezoelectric elements of the nozzles # 1 to # 180 are driven based on the drive signal DRV from the drive signal shaping unit 644B.

<About the head drive signal>
FIG. 8 is a timing chart for explaining each signal. In other words, the timing chart of each signal of the original signal ODRV, the print signal PRT (i), and the drive signal DRV (i) is shown in FIG. Here, PRT (i) is formed from PRT.

  The original signal ODRV is a signal supplied in common to the nozzles # 1 to # 180 from the original drive signal generator 644A. In the present embodiment, the original signal ODRV includes two pulses of a first pulse W1 and a second pulse W2 within a main scanning period for one pixel (within a time during which the carriage crosses the interval of one pixel). The original signal ODRV is output from the original drive signal generation unit 644A to the drive signal shaping unit 644B.

  The print signal PRT (i) is a signal corresponding to the pixel data assigned to one pixel. That is, the print signal PRT (i) is a signal corresponding to the pixel data included in the print data. In the present embodiment, the print signal PRT (i) is a signal having 2-bit information per pixel for the nozzle #i. Note that the drive signal shaping unit 644B shapes the original signal ODRV according to the signal level of the print signal PRT (i) and outputs the drive signal DRV.

  The drive signal DRV is a signal obtained by blocking the original signal ODRV according to the level of the print signal PRT. That is, when the print signal PRT (i) is 1 level, the drive signal shaping unit 644B passes the corresponding pulse of the original signal ODRV as it is to obtain the drive signal DRV. On the other hand, when the print signal PRT is 0 level, the drive signal shaping unit 644B blocks the pulse of the original signal ODRV. The drive signal shaping unit 644B outputs the drive signal DRV to the piezo element provided for each nozzle. The piezo element is driven according to the drive signal DRV.

  The control signal S1 is input to the latch circuit and the data selector as shown in FIG. 7B. The control signal S2 is input to the data selector. The control signals S1 and S2 indicate the timing when the print signal PRT (i) changes as shown in FIG.

  The serially transmitted print signal PRT is converted into 180 pieces of 2-bit data (parallel data) as described below. First, the print signal PRT is input to 360 shift registers. When the pulse of the control signal S1 is input to the latch circuit, 360 data of each shift register is latched. The data selector selects and outputs the data latched by the latch circuit. When the pulse of the control signal S1 is input to the latch circuit, the pulse of the control signal S1 is also input to the data selector. The data selector is in an initial state when the control signal S1 is input. The data selector in the initial state selects the data stored in the shift register W2-i before latching, and outputs it as PRT (i). Next, the data selector selects the data stored in the shift register W1-i before being latched by the pulse of the control signal S2, and outputs it as PRT (i). In this way, the serially transmitted print signal PRT is converted into 180 pieces of 2-bit data. Then, ejection / non-ejection relating to the second pulse W2 is determined by the control signal S1, and ejection / non-ejection relating to the first pulse W1 is determined by the control signal S2.

  When the print signal PRT (i) corresponds to the 2-bit data “01”, only the first pulse W1 is output in the latter half of one pixel interval. As a result, small ink droplets are ejected from the nozzles, and small dots (small dots) are formed on the paper. When the print signal PRT (i) corresponds to the 2-bit data “10”, only the second pulse W2 is output in the first half of one pixel section. As a result, medium-sized ink droplets are ejected from the nozzles, and medium-sized dots (medium dots) are formed on the paper. When the print signal PRT (i) corresponds to the 2-bit data “11”, the first pulse W1 and the second pulse W2 are output in one pixel section. Thereby, a large ink droplet is ejected from the nozzle, and a large dot (large dot) is formed on the paper. When the print signal PRT (i) corresponds to the 2-bit data “00”, neither the first pulse W1 nor the second pulse W2 is output. Thereby, in this section, ink is not ejected and dots are not formed.

  As described above, the drive signal DRV (i) in one pixel section is shaped to have four different waveforms according to four different values of the print signal PRT (i).

  FIG. 9 is a diagram for explaining ink landing positions in bidirectional printing. In the figure, the speed when ink is ejected in the forward path and the backward path is displayed as a vector. Here, the moving speed of the head 41 is Vt in both the forward path and the return path. At this time, the target landing position of the ink in the forward path and the target landing position of the ink in the backward path are both represented by A in the figure. Therefore, it is desirable that the ink ejection speed with respect to the paper S be V1 and be directed to the landing position A aiming at the direction of the vector of DV1 so that the landing position is A in the drawing both in the forward path and in the backward path.

  However, there may be a case where the ink ejection speed is slower than V1. In the figure, the ink discharge speed V2 is shown as a case where the discharge speed is slow. As described above, when the ejection speed is slow, even if ink is ejected at the same timing as described above, the vector direction of DV2 does not face A, and the head movement direction precedes the target landing position A. The ink will land on the side. Then, the ink landing position in the forward path and the ink landing position in the backward path are shifted in the moving direction of the head.

  FIG. 10A is an explanatory diagram of a pattern for inspecting the deviation of the ink landing position. In the figure, a pattern P1 configured by a pattern formed in the forward path and a pattern formed in the backward path is shown. Both the pattern formed in the forward path and the pattern formed in the return path are formed so that dots are aligned in the nozzle row direction in which the nozzles are aligned.

  Again, ink is ejected at a predetermined ejection timing to form these patterns in the forward path and the backward path of the head.For the same reason as described above, the position of the pattern line in the forward path and the position of the pattern line in the backward path are The head movement direction is shifted by Δx. If it is possible to grasp how much the ink landing position is deviated (in this case, Δx), the moving speed of the head is predetermined, so it is possible to determine how long the ejection timing should be shifted. .

  FIG. 10B is an explanatory diagram of the pattern after the ink ejection timing is adjusted. Here, as compared with the case of FIG. 10A, the ink ejection timing in the return path is adjusted so that the ink landing position in the return path is shifted to the right in the drawing by Δx. As a result, the ink was ejected in the forward path and the return path. The inks are arranged so as to match in the moving direction of the head.

  FIG. 11A is a diagram illustrating the relationship between the original signal and the control signal before adjusting the ink ejection timing. In FIG. 11A, the original signal ODRV and the control signals S1, S2 in a period corresponding to the main scanning period for one pixel are extracted from the timing chart in FIG.

  By the way, the control signals S1 and S2 are both generated based on a PTS (Pulse Timing Signal) signal. The PTS signal is a signal that defines the timing at which a pulse is generated in these control signals S1 and S2. The pulse of the PTS signal is generated based on output pulses ENC-A and ENC-B from the linear encoder 51 (detection unit 566). That is, the pulse of the PTS signal is generated according to the movement amount of the carriage 31.

  Therefore, if the generation timing of the original signal ODRV with respect to the control signals S1 and S2 can be shifted, the ejection timing can be changed with respect to the control signals S1 and S2. The timing can also be changed.

  FIG. 11B is a diagram illustrating the relationship between the original signal after adjusting the ink ejection timing and the control signal. Compared with each signal of FIG. 11A, the shape of the original signal ODRV is the same. However, the generation timing of the original signal ODRV is generated prior to the control signals S1 and S2 by Δt before that of FIG. 11A.

  As described above, when the generation timing of the original signal ODRV is shifted by Δt, the generation timing of the drive signal DRV is also advanced by Δt accordingly. Since the ink is ejected by applying the drive signal DRV to the piezo element PZT of the head 41, if the generation timing of the drive signal DRV precedes by Δt, the ink ejection timing precedes by Δt accordingly. become.

  Therefore, as a method for adjusting the ejection timing, Δt is stored in advance in the memory 63 of the printer as a correction amount of the ejection timing corresponding to Δx in FIG. 10A described above. Then, in order to advance the ink ejection timing in the backward path direction of bidirectional printing by Δt, the generation timing of the original signal ODRV is also advanced by Δt, so that the landing positions of the forward path and the backward path can be matched as shown in FIG. 10B. it can.

  The generation timing of the original signal ODRV is changed by changing the generation timing of the original signal ODRV in the original drive signal generation unit 644A.

  Here, the discharge timing in the backward direction is advanced by Δt, but the forward landing timing may be made to coincide as shown in FIG. 10B by advancing the forward discharge timing by Δt. Further, the landing positions of the forward path and the backward path may be matched as shown in FIG. 10B by advancing the discharge timing of the forward path and the backward path by Δt / 2.

  Although the method for delaying the ink ejection timing has been described here, if the generation timing of the original signal ODRV is delayed by Δt with respect to the control signals S1 and S2, the ink ejection timing is set. It goes without saying that it can be delayed.

  Further, the case where only one original signal ODRV is generated has been described. However, when the discharge timing of each color is adjusted in a plurality of ink colors, the original signal corresponding to each ink color is displayed. Generate. Then, the generation timing for the control signals S1 and S2 may be adjusted for each original signal.

  Further, the ink ejection timing is adjusted by changing the generation timing of the original signal with respect to the control signals S1 and S2. However, by changing the position of the pixel to be printed so as to shift in the pixel data, The ink ejection timing can also be adjusted.

  FIG. 12 is a graph showing the relationship between temperature and ink viscosity with respect to temperature. In the figure, the viscosity of a certain ink with respect to temperature is shown. Generally, when the temperature is lowered, the viscosity tends to increase. In particular, the degree of increase in the viscosity is large on the low temperature side. When such an ink is used, if the temperature of the ink becomes too low, the discharge speed may be drastically decreased due to a rapid increase in the viscosity of the ink. Then, as described above, even if the ink ejection timing is advanced, the ink landing position cannot be adjusted, and when the target landing position in the forward path and the target landing position in the backward path are the same position, the landing positions in both are determined. There are cases where they cannot be matched.

  Therefore, in the present embodiment, as described below, when the temperature related to the head 41 is higher than the predetermined temperature, the printing speed is secured while performing the bidirectional printing while correcting the ejection timing as usual to ensure the print quality. To speed up. On the other hand, when the temperature related to the head 41 is equal to or lower than the predetermined temperature, the ink discharge speed is too slow and the predetermined print quality cannot be ensured even if the discharge timing is corrected. Thus, the target landing position on the forward path and the target landing position on the return path are made to coincide.

FIG. 13 is a flowchart of the printing process in the first embodiment.
When printing is started, the temperature of the head 41 is acquired via the thermistor 502 (S102). The temperature of the head 41 is acquired for each page of the paper S to be printed. That is, the temperature of the head 41 is acquired immediately before printing one sheet of paper S.

  Next, it is determined whether or not the acquired temperature is equal to or lower than a predetermined temperature (S104). Here, the predetermined temperature is set to 10 degrees Celsius. When the temperature related to the head 41 is higher than the predetermined temperature, printing is performed by ejecting ink in the forward path and the backward path with the ejection timing adjusted as described above (S106). The moving speed of the head at this time is a preset normal speed, which is a speed corresponding to Vt shown in FIG.

  On the other hand, in step S104, when the acquired temperature is equal to or lower than the predetermined temperature (that is, the acquired temperature is 10 ° C. or lower), printing is performed while slowing the moving speed of the head 41 so that the ink landing position is appropriate. (S108).

  FIG. 14 is a diagram illustrating the ink landing position when the moving speed of the head 41 is slowed. In the figure, the ink ejection speed V1 when the acquired temperature is higher than the predetermined temperature and the speed Vt when the head 41 is moved at a normal speed are displayed in vector form. The drawing also shows the ink ejection speed V2 when the acquired temperature is equal to or lower than the predetermined temperature. When the acquired temperature is equal to or lower than the predetermined temperature, the viscosity of the ink is higher than when the temperature is higher than the predetermined temperature. Therefore, the discharge speed V2 is slower than the discharge speed V1.

  In this way, when the moving speed of the head 41 is moved at the normal moving speed Vt when the ejection speed is slow, the ink landing position will land at a position that precedes the moving direction of the head 41. This is as described in FIG. Therefore, in this embodiment, as described above, printing is performed at a slower moving speed of the head 41 so that the ink landing position is appropriate. In the figure, the moving speed Vs of the head 41 having a reduced moving speed is shown. The moving speed Vs of the head 41 at this time is set to a speed at which the vector DV3 combined with the ink ejection speed V2 overlaps DV1. In this way, the ink landing position can be adjusted to an appropriate position by slowing the moving speed of the head 41 by the amount that the ejection speed has slowed. Then, when the target landing position in the forward path and the target landing position in the backward path are the same position in the main scanning direction, the landing positions of both can be matched.

  When the printing of one sheet S is completed in step S106 or step S108 by the printing method as described above, the printing process ends. Here, if there is further paper to be printed, the above printing process is repeated in the same manner.

  Note that the printer according to the present embodiment includes a plurality of nozzle rows for ejecting a plurality of colors of ink. Therefore, when bidirectional printing is performed, it goes without saying that the ejection timing is corrected for each nozzle row as described above.

=== Second Embodiment ===
FIG. 15 is a flowchart of print processing in the second embodiment.
In the second embodiment, as the temperature related to the head becomes lower, (1) the moving speed of the head 41 is set to the normal speed Vt for bidirectional printing, and the bidirectional printing is performed. (2) the moving speed of the head 41 is changed to the bidirectional printing. Bidirectional printing with slow speed Vs (3) Unidirectional printing with head 41 moving speed normal speed for unidirectional printing (4) Unidirectional printing with head 41 moving speed slow for unidirectional printing, Switch as follows. In addition, below, the 1st temperature, 2nd temperature, and 3rd temperature are shown as a threshold value of temperature, but these temperature shall be high in order of 1st temperature, 2nd temperature, and 3rd temperature. For example, the first temperature is 10 ° C., the second temperature is 5 ° C., and the third temperature is 0 ° C.

  When printing is started, the temperature of the head 41 is acquired via the thermistor 502 (S202). Again, the temperature of the head 41 is acquired for each page of the paper S to be printed.

  Next, it is determined whether or not the acquired temperature is equal to or lower than the first temperature (S204). If the acquired temperature is not equal to or lower than the first temperature, printing is performed by ejecting ink in the forward path and the backward path while correcting the ejection timing with the correction value (S206).

  On the other hand, if the acquired temperature is equal to or lower than the first temperature, it is determined whether or not the acquired temperature is equal to or lower than the second temperature (S208). If the acquired temperature is not less than or equal to the second temperature, the moving speed of the head 41 is slowed down, and when the target landing position on the forward path and the target landing position on the return path are the same position, Printing is performed by ejecting ink so as to match (S210). Since the movement speed of the slowed head 41 is the same as that described in the first embodiment, the description thereof is omitted.

  In step S208, if the temperature of the head 41 is equal to or lower than the second temperature, it is determined whether or not the temperature is equal to or lower than the third temperature (S212). If the temperature is not lower than the third temperature, the moving speed of the head is only the movement in one direction while moving the head at the same speed as when bidirectional printing was performed in step S206 (in the forward path and the backward path). Either one) Printing is performed by discharging ink. In this way, if ink is ejected in both the forward path and the backward path, even if these target landing positions are shifted, ink is ejected only in one direction. It is possible to prevent the problem that the ink landing positions do not match. However, the printing time is longer than that for bidirectional printing.

  When the printing time in step S210 and the printing time in step S214 are compared, the movement of both heads 41 is such that the printing speed per sheet is at least faster in step S210 than in step S214. The speed is adjusted. In other words, the moving speed of the head 41 is adjusted so that the area of the image formed per unit time is larger in the printing in step S210 than in the printing in step S214.

  In step S212, when the temperature of the head 41 is equal to or lower than the third temperature, the head 41 is moved at a speed slower than the speed at which the head is moved in step S214, and only in one direction (outward and backward paths). Either one of these is performed by discharging ink. In this way, even when the ink ejection speed becomes slower, the interval between the ink landing positions in the moving direction of the head 41 can be prevented from becoming wide.

  In this way, when printing of one sheet S is completed in step S206, step S210, step S214, or step S216, this printing process is ended. Here, if there is further paper to be printed, the above printing process is repeated in the same manner.

  By doing so, the deviation of the ink landing position can be reduced.

=== Other Embodiments ===
In the above-described embodiment, the printer 1 has been described as the liquid ejecting apparatus. However, the present invention is not limited to this, and other fluids (liquid, liquids in which particles of functional materials are dispersed, gels, and the like) are not limited thereto. Such a fluid can also be embodied in a liquid ejection device that ejects or ejects the fluid. For example, color filter manufacturing apparatus, dyeing apparatus, fine processing apparatus, semiconductor manufacturing apparatus, surface processing apparatus, three-dimensional modeling machine, gas vaporizer, organic EL manufacturing apparatus (especially polymer EL manufacturing apparatus), display manufacturing apparatus, film formation You may apply the technique similar to the above-mentioned embodiment to the various apparatuses which applied inkjet technology, such as an apparatus and a DNA chip manufacturing apparatus. These methods and manufacturing methods are also within the scope of application.

  The above-described embodiments are for facilitating the understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof.

1 printer,
20 transport unit, 21 paper feed roller, 22 transport motor,
23 transport roller, 24 platen, 25 discharge roller,
30 Carriage unit, 31 Carriage,
32 carriage motor, 40 head unit, 41 head,
50 detector groups, 502 thermistors,
51 Linear encoder, 52 Rotary encoder,
53 Paper detection sensor, 54 Optical sensor,
60 controller, 61 interface unit, 62 CPU,
63 memory, 64 unit control circuit,
100 printing system, 110 computer, 120 display device,
130 input device, 130A keyboard, 130B mouse,
140 recording / reproducing apparatus, 140A flexible disk drive apparatus,
140B CD-ROM drive device

Claims (8)

A head for discharging liquid onto the medium;
A head moving unit for moving the head in the moving direction;
A temperature acquisition unit for acquiring a temperature related to the head;
A control unit for controlling the head moving unit and the head, wherein when the temperature acquired by the temperature acquisition unit exceeds a first predetermined temperature, the head is moved at a first speed to discharge the liquid; A controller that moves the head at a second speed slower than the first speed to discharge the liquid when the temperature acquired by the temperature acquisition unit is equal to or lower than the first predetermined temperature;
A liquid ejection apparatus comprising:   The liquid ejection apparatus according to claim 1, wherein the determination whether the temperature acquired by the temperature acquisition unit is equal to or lower than the first predetermined temperature is performed for each page of the medium.   The liquid ejection apparatus according to claim 1, wherein the determination as to whether or not the temperature acquired by the temperature acquisition unit is equal to or lower than the first predetermined temperature is performed at predetermined time intervals. The controller is
When the temperature acquired by the temperature acquisition unit exceeds the first predetermined temperature, the head is moved at the first speed, and control is performed in a first mode in which the liquid is discharged in the forward path and the return path in the movement direction,
When the temperature acquired by the temperature acquisition unit is equal to or lower than the first predetermined temperature and exceeds a second predetermined temperature lower than the first predetermined temperature, the head is moved at the second speed, Control in the second mode in which the liquid is ejected in the forward path and the return path,
When the temperature acquired by the temperature acquisition unit is equal to or lower than the second predetermined temperature, control is performed in a third mode in which the liquid is discharged when the head is moving in either the forward path or the return path in the movement direction. The liquid ejection apparatus according to claim 1. The controller is
When the temperature acquired by the temperature acquisition unit is equal to or lower than the second predetermined temperature and exceeds a third predetermined temperature lower than the second predetermined temperature, the head moves in one of the forward path and the return path in the moving direction. And controlling in a third mode for discharging the liquid when
When the temperature acquired by the temperature acquisition unit is equal to or lower than the third predetermined temperature, the head is moving at a slower speed than in the third mode in either the forward path or the return path in the movement direction. The liquid ejection apparatus according to claim 4, wherein the liquid ejection device is controlled in a fourth mode in which the liquid is ejected.   The moving speed of the head is set so that an area of an image formed per unit time on the medium is larger in the second mode than in the third mode. The liquid ejection device according to any one of 5.   The liquid discharge apparatus according to claim 1, wherein the change in viscosity with respect to the temperature of the liquid is steeper as the temperature of the liquid decreases. Obtaining a temperature associated with a head that ejects liquid onto the medium;
When the temperature exceeds a predetermined temperature, the head is moved at a first speed to discharge the liquid. When the temperature is equal to or lower than the predetermined temperature, the head is moved at a second speed that is slower than the first speed. Moving and ejecting the liquid;
A liquid ejection method comprising:

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